الفهرس 
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Abstract
Summary
Soft-tissue masses usually represent a diagnostic dilemma, since there is a large and heterogeneous group of lesions, including both neoplastic (benign and malignant) and non-neoplastic lesions.
Soft tissue tumors are classified according to their similarity to normal tissue. Thus, the current WHO classification includes adipocytic tumors, fibroblastic/myofibroblastic tumors, fibrohistiocytic tumors, tumors of smooth muscle and skeletal muscle, pericytic tumors, and vascular and chondro-osseous tumors. Neoplasms for which there is no known comparable normal tissue are grouped together in the last group of tumors of uncertain differentiation (318).
Whenever a patient presents with a soft tissue mass, a detailed history should be taken (especially patient age, lesion location and duration of symptoms) and a thorough clinical examination performed. Further imaging is often required; the major role of imaging is detection, grading (characterization and tissue-specific diagnosis), staging, and follow-up (322).
The imaging evaluation of a patient with a suspected soft tissue tumor requires methodological approach that recognizes the benefits and limitations of the imaging techniques.
Despite the superiority of MR imaging in delineating soft tissue tumors, it remains limited in its ability to characterize them precisely. The majority of lesions remain nonspecific, however, there are instances, in which a specific diagnosis may be made or strongly suspected on an analysis of the MR imaging features. This is usually done on the basis of lesion signal intensity, pattern of growth, location, and associated signs and findings. (10)
Algorithms are intended to illustrate a systematic approach for evaluating soft-tissue masses on the basis of their predominant SI on MR images.
In some cases, the algorithms can lead to a specific tumor. In other cases, the analysis leads to a tissue category that includes both benign and malignant diagnoses. This information must be combined with clinical data, lesion location, relevant additional MR imaging features to arrive at a more conclusive diagnosis or differential diagnosis (9).
In conclusion
By systematically using clinical history, lesion location, mineralization on radiographs, and SI characteristics on MR images, the radiologist can develop a short and appropriate differential diagnosis.
The MR images of benign fatty tumors, pigmented villonodular synovitis, ganglia, hemangiomas, and hematomas can be quite characteristic, although not pathognomonic. There are no single reliable criteria to distinguish the MR images of malignant from benign soft-tissue tumors. The MR imaging characteristics most likely reflect the underlying lesion morphology (fat content, hemosiderin deposition, cyst formation, hemorrhage, etc.) and not the specific histology.